Created rest route to perform authentication

src/Service/RestTokenServiceInterface.php

@@ -0,0 +1,25 @@
+<?php
+namespace Acelaya\UrlShortener\Service;
+
+use Acelaya\UrlShortener\Entity\RestToken;
+use Acelaya\UrlShortener\Exception\AuthenticationException;
+use Acelaya\UrlShortener\Exception\InvalidArgumentException;
+
+interface RestTokenServiceInterface
+{
+    /**
+     * @param string $token
+     * @return RestToken
+     * @throws InvalidArgumentException
+     */
+    public function getByToken($token);
+
+    /**
+     * Creates and returns a new RestToken if username and password are correct
+     * @param $username
+     * @param $password
+     * @return RestToken
+     * @throws AuthenticationException
+     */
+    public function createToken($username, $password);
+}